Guardian Angel
by Taliya
Summary: Shinichi's stint as Conan did much more than change him physically. When the detective's memory begins to fail him, what other recourse does a worried KID have but to suggest to Haibara to shrink him once more? Future fic. Familial Kaito-Shinichi-Ai. Rated for language. Prequel to "Puck's Unveiling".
1. I: Destruction

Detective Conan and Magic Kaito characters, settings, and ideas do not belong to me but to Aoyama Gōshō.

* * *

Guardian Angel

By Taliya

* * *

I: Destruction

* * *

By themselves they were little, innocuous things that he noticed. But cumulatively, these little things were dangerous, particularly in the line of work in which one thirty-five-year-old Kudou Shinichi worked. As a homicide detective, it was an extremely important asset for him to have an eidetic memory, as well as one of the quickest minds he had ever had the pleasure of matching wits against. It was what made heists with his particular participation so much fun. And yet as of late, heists with his participation worried him more often than not.

There would be the taunts, and then there would be the chases. As Tantei-kun, his intellect was on par, though physically he sometimes needed a little help. As Meitantei-san, he should have been in all respects, an equal of Kaitou KID. And yet now it was his intellect that was failing him. Midway through chases it would leave him stumbling, wondering why he was at that particular location or what exactly was he searching for. Because Snake and his men had been put behind bars, as well as Kudou's own Black Organization, KID felt little worry about the detective's physical safety at his heists, apart from his own daredevil stunts to capture him.

They were few and far in between at first, but they progressively happened more frequently during his continuing search for Pandora—which after nearly twenty years of searching, he was beginning to think the damn stone did not actually exist. And after hanging around the Task Force masquerading as one of their own on multiple occasions, he had discovered that Kudou's apparent memory lapses extended to his work as a professional private investigator and Inspector for Division One's Homicide Unit. It was, frankly, worrying.

The detective himself seemed to brush off the incidents with his usual aplomb, though KID was not a master of Poker Face for nothing. He had seen the glint of anxiety in the man's eyes after a blank out, the momentary disorientation that came with suddenly realizing you were in a different time and place than what you had last remembered. Whenever one of these lapses in memory occurred in KID's presence, he mentally catalogued the situation, the day, the time, and the duration. There was no pattern to them, nothing discernable to someone of even his intelligence with an affinity for riddles and tricks. The only thing he knew with absolute certainty was the fact that these episodes were increasing in frequency and duration.

The phantom thief feared he knew exactly what was happening to the detective, but he wanted a second opinion to ensure he was not jumping to conclusions. And yet something had to be done, or the Kudou Shinichi that Kaitou KID had come to regard as a rival, ally, and friend, would lose his mind—literally.

* * *

"Good evening, ojou-san." The voice came from behind her and she jumped off the couch, eyes wide and heart pounding at the intruder into the otherwise quiet home of Haibara Ai. It was now one in the morning and the twenty-six-year-old scientist sat alone in the living room, typing away on her laptop. As it was, she had barely refrained from screaming and reflexively throwing her laptop in the air.

The ghostly white outfit of Kaitou KID stood out in the shadowed gloom of her living room, illuminated only by the dim lamp on the end table and the luminescence of the full moon. "Pardon my intrusion," he murmured with a tip of his head, and only then did she realize that he had slipped out of his normal white leather shoes and exchanged them for a pair of guest house slippers. He stood in the empty space between the front door and where she sat on the couch, hands tucked into his pockets and head tilted casually with a small smirk on his lips. The brim of his top hat concealed the upper half of his face in shadows from the moonlight while the glint off his monocle from her lamp further sent his features into darkness.

"KID-san," she greeted once her heart had resettled itself in her chest from where it had lodged itself to her throat. Her usual cool demeanor reasserted itself as she eyed the infamous Magician Under the Moonlight after setting her laptop on the coffee table. "What brings you to the… inside of my door?" In all honesty she was not surprised that he had found her here, for had he not disguised as her adult self and faked her death on the train almost two decades ago? Likely he kept additional tabs on people close to those who pursued him—for instance, Kudou Shinichi.

In spite of the shadows that blanketed his face, she knew the exact moment when his focus sharpened solely on her, and it sent chills down her spine. It was different from the sensation that came from being watched by a member of the Black Organization. KID's gaze was equally intense, true, but without the murderous intent that she could easily feel in her bones, and she had never once felt threatened by the magician. "Haibara Ai," he announced, and there was no trace of the phantom thief's normal joviality in his voice. "Miyano Shiho. _Sherry_." She violently flinched at the mention of her former Organization codename. Nix that last thought.

"What do you want?" she asked warily, fervently wishing for once that she did not live by herself and still lived with Professor Agasa. Despite the Black Organization's demise, Miyano Shiho had opted to remain as Haibara Ai, while Edogawa Conan had disappeared and Kudou Shinichi had returned to the public eye. And yet despite the freedom her younger form's anonymity provided, she felt completely cornered in her own home by a nonviolent thief.

"Your help," he replied simply.

It took a moment for her brain to process the two words. "My… help?" she repeated, confusion evident in her tone. "My help on what?"

KID folded his arms across his chest, a frown curving his lips as he studied the once-shrunken scientist. Haibara Ai had made a name for herself in the world of biochemistry, neurology, pharmacology, and genetics, having opted to skip multiple grades after the fall of the Black Organization. She had been accepted into Touto University at age twelve, graduated with multiple doctorate degrees at age seventeen, and currently worked as a tenured professor at her alma mater. "There's something wrong with Meitantei-san," he said baldly, and Ai's heart skipped a beat in fear at the statement.

 _Is Kudou-kun suffering from some latent side effect of the apoptoxin I don't know about?_ she wondered worriedly.

"Has he said anything to you about this?" the phantom thief asked.

Ai shook her head negatively. "No, he has not," she answered, and she felt her anxiety ratchet up by a few notches. "What are his symptoms?"

"Mental lapses with disorientation afterwards in regard to time and place, difficulty solving cases, extreme irritability, forgetfulness regarding where he's placed individual items… independently, those could be written off as due to exhaustion, but the increasing frequency and duration of these mental blanks of his has me… worried. He'll even blank out halfway through a chase during my heists, then come to only to blink and wonder _why_ he was where he was, much less attempt to catch me while I'm standing nearby while he's trying to keep his panic down. I have not observed or heard of any indication of trauma to that noggin of his, so I believe cranial injury is not the cause. I can't even begin to imagine what he must be like when he blanks on one of his cases."

The scientist felt her heart sink as she added up the indicators even as he confirmed her suspicion of the thief keeping an eye on all of them. She was willing to bet that KID also kept tabs on the other members of the disbanded Shounen Tantei-dan, as well as the Mouris. "You know what those symptoms mean, don't you?"

KID sighed deeply. "Yes," he admitted reluctantly, "I do."

"Early-onset Alzheimer's disease," they both said, verbalizing and confirming their suspicions to the other.

Ai clenched her fists. It truly was not fair, she reflected, for Shinichi to suffer in this way. His intellect was his most prized asset, and to have that taken away was simply unfathomable. And yet here she stood, facing an internationally wanted criminal who had come to her with concerns over their mutual friend, hoping she had some idea of how to help him. "I'll run some sequencing tests on his DNA to see if I can pinpoint which genes are responsible. From what I know, early-onset Alzheimer's does not seem to run in his family."

The thief was silent, mulling over thoughts in the privacy of his mind. His lips tightened into a straight line, and Ai knew he had just thought of something. "Do you think," he began hesitantly, "that his repeated age changes had something to do with it?"

The question hung in the moonlit silence between them, and Ai felt her chest squeeze tightly with guilt. _Is this to be another repercussion Kudou-kun must suffer from that I am responsible for? Will I ever be able to atone for it and for once help the man who I owe my life to instead of simply piling on burden after burden?!_ She clenched her jaw and willed herself not to cry, even as she felt the telltale burning in her sinuses that indicated otherwise. _Why can't I do anything right by Kudou-kun?!_

"Considering," the magician continued, unaware of the scientist's silent self-flagellation, "that he has had to age and de-age roughly ten years in the span of two minutes, don't you think the possibility of genetic mutation to be incredibly high? I don't think the shrinking is the problem; I think it is the growing that is the problem. When he ages that rapidly, his cells have to perform mitosis at an exponential rate, thereby significantly increasing the chances of his DNA replicating incorrectly. And since this is somewhat of an age-related disease, do you think it's possible to 'reset the clock', so to speak—for Meitantei-san?"

Ai snapped out of her mental lashing at the gentleman thief's latter question. "You mean…" she murmured, catching onto his train of thought, "give Kudou-kun the apoptoxin to de-age him again?"

The phantom thief nodded solemnly, once. "Yes."

"But I don't—" she stuttered in sudden anxiousness, "—I don't remember the original formula anymore!" Once the antidote had been made, she had burned and destroyed all the data she had compiled regarding APTX 4869. "And I've destroyed all the data pertaining to that poison."

KID regarded her contemplatively. "Could you back it out of the antidote?"

The young professor clenched her fists. She could do it; she knew she could. But did she want to recreate the very same drug that had ruined Shinichi's life once already?

"Even if you make it, it's his decision if he wants to take it," the thief murmured as if reading her thoughts. "All you'd be doing is giving him a choice."

Ai let out a shaky breath. "It seems," she said resignedly, scornfully, "that I am to be forever tied to that _fucking_ drug."

"There's no need to make it if it upsets you that much, ojou-san," KID said in a low, soothing croon. "Your mental health needs to be taken into consideration as well."

KID was wrong there. Her mental health took a backseat when it came to her friend—it always had. She had caused him enough suffering, and she was determined not to add to it. She would recreate the drug, to give him a shot at halting the disease in its tracks. The researcher performed some calculations in her head. Giving Kudou the same dosage as before would likely throw him back ten years in age, turning him twenty five; however there was the added problem of the antidote that she knew for a fact still roamed in his bloodstream. As it stood, the poison and antitoxin balanced each other out. Giving him another dose equal to the original probably would not last him as long, as his body would replicate the antidote and therefore force his re-aging much more quickly. By her estimate, it would give her maybe five years' time to determine what genes had changed through his back and forth age shifts. There was new research on Alzheimer's being published all the time, though the bulk of the work was performed chiefly by the Americans. She had skimmed a recent article in _Nature_ on a possible cure for Alzheimer's that had been tested on rats, which seemed to reverse the effects of the disease if caught early enough—before damage became permanent to the neural pathways of the brain.

"I might need to make a few trips to America in the coming years while I reformulate the apoptoxin," she murmured thoughtfully.

KID swiveled on his heel to face the window, tilting his head back to regard the moon, and Ai caught his illuminated profile silhouetted against the darkness. From what she could tell, he looked remarkably similar to the detective, provided he was not wearing a disguise. "Do you think it's a viable solution?" he asked sotto voce, his somber expression a far cry from his usual cheerful smirk as his eyes watched the celestial orb.

Maybe it was a trick of the light, or maybe it was the gravity of the situation they found themselves in, but for a moment Ai saw Kaitou KID not as the phantom thief he presented himself to the world as, but a protective being who soared through the skies on wings of white, and she could not help but think, _Guardian angel_. "It's a possibility," she conceded. "I'll need to call in Kudou-kun and run a few tests on him." She glanced at the second bedroom of her three-bedroom house, which she had renovated into a fully-functioning, state-of-the-art laboratory. The perks of being an internationally acclaimed and tenured research scientist—she got a _lot_ of research funding. "I'll call him at a more reasonable hour to begin the initial bloodwork," she said. "Thank you for bringing this to my attention, KID-san."

"No, ojou-san," replied the thief as he melted into the shadows. "Thank _you_ for listening to my concerns."

* * *

Kudou Shinichi slunk into the home of Haibara Ai at a quarter past nine on a Friday morning following a summons via a mobile call that had woken him at eight. Her message had been terse and concise. _"Come by my house as soon as you can. Call in sick if you must. No caffeine until I have your blood."_ It left him feeling anxious in a vague but looming sort of manner even as he humorously pondered what would happen if anyone other than him had received such a message. No doubt Division One would have been called thinking this was likely a premeditated murder between close friends or something. _Definitely friends, but the murder part might be accidental._

Lately, he had been having problems recalling details that before he had not issues doing. Not only that, but whenever he was scouring a crime scene, sometimes he felt as though pieces that normally snapped almost instinctively together for him seemed to no longer fit, like trying to fit a hendecagonal peg into a dodecagonal hole—almost, but not quite right.

The mental blanks were the worst. He would be going about his day, cataloguing details of a crime scene, then blink and realize that not only had ten minutes passed, but that he had _no idea what he had done during those ten minutes_. It was terrifying in a way that he could not describe, and though he had covered it well, he was now almost always in a constant state of unease that left him tired and irritable.

Then there were the budding but equally worrying spatial issues. Kudou Shinichi lived by himself in the Western-style mansion his parents had bought. His childhood sweetheart, Mouri Ran, was now happily married to Hondou Eisuke. Every day he would navigate his way from his house to TMPD headquarters, the streets and back roads he used as familiar to him as the back of his hand. It normally took him twenty minutes at a brisk walk; lately it was taking anywhere from thirty minutes to an hour, for oddly enough he would inevitably, inexplicably, find himself lost.

He kept his worries to himself for the most part, simply because he did not want to let other people down—not Megure, not Takagi or Satou, and most definitely not the loved ones of a murder victim. To the wider world, Kudou Shinichi was the brilliant, unflappable detective comparable to the fictional Holmes, but to those that truly knew him, Kudou Shinichi was a sensitive, compassionate individual who took each death personally.

"Ojama shimasu," the detective announced sleepily, swapping his work leathers for house slippers in the genkan.

"In the lab," replied Haibara's voice, and Shinichi dutifully shuffled into the second bedroom, now filled with expensive laboratory equipment and compounds. The lab was internally connected to the third bedroom, which was where Shinichi generally stayed if there was some overnight test the scientist required him to stay for. "Blood work," she said curtly from her position on the step stool as she hovered over a light microscope, and the detective huffed as he sat on the chair next to a table and rolled up his sleeve.

"So what are we testing for this time, Haibara?" he asked with a yawn as the scientist gathered up the necessary instruments to draw blood and set them on a tray.

"Syphilis," she answered sedately, setting the tray on table he rested his exposed arm on.

Shinichi blanched, suddenly fully awake. "Sy—syphilis?!" he squeaked.

Ai watched him squirm for a moment or two before she said flatly, "Joke, Kudou-kun, joke."

"Damn it, Haibara," the detective swore, and Ai cracked a tiny smirk in his direction as she pulled on latex gloves and attached the first of three Vacutainers to the tubing of a butterfly needle. "Not funny." She tied the rubber tourniquet tightly around his upper arm before prodding the inside of his elbow with her fingertips, checking for the blood vessel she normally used to collect blood samples from. She wiped the area with an alcohol pad before expertly sliding the needle under the skin and catching the vessel on the first attempt. The pair waited quietly for the container to fill with the dark crimson fluid before Ai detached the filled tube and replaced it, repeating the process once more before she extracted the butterfly needle.

A minute later Shinichi had a small patch bandage adhered over the prick mark, the newest of many he had acquired over his years of acquaintanceship with the researcher as her pet guinea pig. Honestly, if anyone did not know him better, they would have thought he was a recreational cocaine or heroin user. He rolled down his sleeve with a sigh, buttoning the cuff of his sleeve. "So what are you really checking for?" he asked his longtime friend.

She gave him an appraising, reproachful stare before she answered, "A little bird told me about your recent memory lapses, Kudou-kun."

Shinichi stiffened. He had been careful not to let on to anyone about those gaps in his memory. "Who told you?" he inquired seriously.

Ai ran his blood through a centrifuge to separate out the plasma from the blood cells, replying cryptically, "A mutual friend of ours with your best interests at heart."

No amount of wheedling, pleading, threatening, or annoying could make the professor reveal who her source was, and so Shinichi gave up trying to pry the answer out of her, though _she_ managed to extract a promise out of him to report every incident to her immediately. Instead, he had sulkily bid her good day and had gone to police headquarters to review older cold cases. He settled himself at his desk amidst the others used by Division One's Homicide Unit, and there Shinichi spent the rest of his morning, munching on two anpan buns and drinking the terrible break room coffee. The detective took note of how long it took for him to resolve a case and noticed that it took longer than before. He felt more uneasy after this observation, for was he losing his mind?

He was in the midst of an absentminded staring contest with a case from five years back when there was an explosion of noise from the floor below, though it was muffled by a meter of concrete that separated the floors. "KAITOU KID, YOU BASTARD! I WILL GET YOU THIS TIME!" The detective blinked, recognizing the voice as Superintendent Nakamori Ginzo's and belatedly realizing that a new heist notice had likely been sent out. Deciding he could use a break from the cold cases, Shinichi stood, stretched his back, and ambled towards the stairwell after informing Senior Superintendent Megure Juuzo of his future whereabouts.

"—dou-san? Kudou-san?"

Shinichi blinked, jerking back as Inspector Satou Miwako waved a hand before his face. "Yes…?" he asked uncertainly, wondering with dread curling in his stomach if he had just had another "episode." He, Satou, and her partner Takagi Wataru were standing on the landing between floors in the stairwell.

"Um… Kudou-san," the assistant inspector said worriedly, "you were staring at the wall in here for the past fifteen minutes."

 _Fifteen minutes…_ Shinichi processed, _I was out for fifteen minutes?!_ Outwardly, he remained calm. "Sorry," he apologized with a chuckle, "just got caught up thinking about something." _At least I wasn't actually doing anything, I think… but where was I going?_

He quickly mentally backtracked and recalled that he had been on his way downstairs to Inspector Nakamori's office to see the newest KID heist notice. "Ah, I was going to take a look at Kaitou KID's latest heist note," he explained, walking down the stairs to the next floor with the other two officers. "See you." He shot a quick text message to Haibara and exited the stairwell to the floor housing the Kaitou KID Task Force. The Division Two Kaitou KID Unit was in total chaos. Most of the men were conducting various internet searches on computers, while others were pouring over maps with the highlighted location of museums, galleries, and hotels. Nakamori himself was glaring at the notice, a vein visibly pulsing in his temple. "Damn you, KID," he snarled.

"Nakamori-keishi," Shinichi greeted the growling man, "Mind if I take a look?"

"Ah, Kudou-keibu," Nakamori acknowledged grudgingly, "Maybe you'll have better luck than us." The superintendent slid the note across his desk, and Shinichi flipped it so that he could read it properly:

* * *

 _When Coyoxauhqui's rounded blush fully flees,_

 _I will come for the Eye of Mictlantecuhtli_

 _On wings opposing Tlalocayotl and Vitzlampaehecatl._

 _-Kaitou KID_

* * *

The focus was on… something to do with Mesoamerican civilizations. Mayan, Aztec, Olmec, or perhaps even Toltec, considering the spelling and pronunciation of the names of these deities… Something about Mictlantecuhtli and cannibalism stirred in his mind… why could he not think straight? He had studied Bronze Age civilizations for fun upon regaining his body and enrolling at Touto University, so why could he not recall details like these? Shinichi shook his head distractedly, ruffling his hair in agitation.

"Something wrong, Kudou-keibu?" asked Nakamore with a hint of concern in his voice.

Shinichi blinked rapidly, the sense of unease building beneath his sternum. _Haibara,_ he thought with rising panic, _Haibara would have an idea of what's happening._ "Just thought of something," Shinichi answered distractedly. "Excuse me," the inspector said before fairly fleeing from the puzzled superintendent. Shinichi ran, hoping his increasingly-wayward sense of direction would lead him to the scientist's home, and not some random street. His luck seemed to hold for once, for he pounded on her front door frantically. The thought that she might be at the university teaching never once occurred to him.

The door suddenly opened, and he barely refrained from accidentally pummeling his friend in the face. "What _is_ it, Kudou?" she snapped curtly, dropping the honorific in her irritation, though with one look at the wildness in his eyes she quickly and wordlessly ushered him inside and into the lab. "Symptoms?" she asked, all business as she sat him in the same chair he had inhabited that morning and grabbed her stethoscope while wheeling over a sphygmomanometer.

With ease she rolled his shirtsleeve up and wrapped the Velcro cuff around his bicep, popping the earpieces of her stethoscope into her ears and sliding the diaphragm beneath the sleeve before inflating it. The scientist took note of his beats per minute, as well as his blood pressure as he murmured, "I texted you about the mental lapse in the stairwell, but while I was reading KID's latest heist notice, I—I panicked." The inspector squeezed his eyes shut as he replayed the scene in his mind. "I recognized the names he used in his note, but I could not remember the details. It's like having a word at the tip of your tongue; I _knew_ but did not _know_. It's like trying to grab smoke—you know it's there because you can see it, smell it, but you can't touch it—you can't tangibly confirm that it exists." His lashes slowly parted and his gaze rose to meet hers. "Haibara," he pleaded with quiet fear and worry and a hundred other nameless emotions shining in his eyes, " _What is wrong with me?_ "

She studied her patient critically before sighing deeply and Shinichi inexplicably felt as though a giant weight had settled on his friend's shoulders. "Let's get into the car and head to campus so that I can run some tests; I'll explain along the way." She released him from the sphygmomanometer cuff and set her stethoscope on the countertop, disappearing into her house to gather her keys and purse before returning to grab a tray of samples—likely his blood—she had tucked into a travel-safe container. The pair hopped into her car and braved the lunchtime traffic.

"Kudou-kun," she began, eyes focused on the road, "What do you honestly think is happening to you?"

Shinichi sighed, ruffling his hair in his apprehensiveness. "If I were trying to be funny, I'd say aliens are slowly taking over my brain, but…" He pinched the bridge of his nose, and in the sunlight it was plain to see that this was taking a toll on the detective's health: there was a bruised smudge under the eye she could see, and his complexion had taken on a waxy pallor. "I'd guess Alzheimer's, early onset, but my family has no history of the disease."

Ai blew a sigh through her nose. "I didn't think you had it either, but that was what the blood work this morning was for: to check for the specific genes that trigger early onset. I have a preliminary analysis done, but I'd like to take a look at the inside of your head before I assume anything." She flicked on her right turn signal as she waited at a light. "The running theory right now is that all the times you've had to grow back to your true age have led to faulty replication of your DNA during accelerated mitosis, which might be why you're showing symptoms now." Her breath caught, as if she wanted to say more but held back.

The detective blinked, waiting for her to continue, but she remained quiet for the remainder of the trip. Shinichi grew decidedly unhappy with the silence. " _Haibara…_ " he verbally nudged with a growl as they approached Touto University's campus.

"He's suspected for a while when you first began to manifest symptoms," she admitted at last as they eased their way through throngs of students. "That's why he came to me last night."

"Who?" the inspector asked, still immensely curious from this morning.

The scientist slowed as she pulled into the faculty parking lot near the building her office was located in. She unbuckled herself before catching Shinichi's eye and replying, "Kaitou KID." Shinichi sat, poleaxed, as Ai retrieved her samples from the back seat. "Come along, Kudou-kun," she called, and he mechanically exited the car and followed her along as his brain tried to process the fact that KID had _snitched_ on him. To _Haibara._

 _… The bastard._

The professor easily navigated her way through hallways, unlocking a nondescript door and ushering him inside the empty room. The interior was that of a large laboratory sectioned off by sturdy walls, and filled with various types of medical machinery. Shinichi recognized none of them. She sat him on one of the cushioned tables normally found in doctor's offices and hurried over to a stainless steel refrigerator marked with a bright radioactive warning sticker, removing a small steel tube. "I want to conduct a brain scan on you, Kudou-kun," she explained as she set up as though she were going to take a blood sample. But instead of a Vacutainer and butterfly needle, she attached the steel tube to a needle and inserted a plunger to form a syringe. "This is florbetaben, a radioactive Fluorine-18 isotope commonly used to diagnose Alzheimer's. It helps with the imaging of beta amyloid plaques that form along the neural pathways in the brain. Florbetaben has a 110-minute half-life, so you should read clean on a Geiger counter after twelve hours or so." She quirked an amused eyebrow at him and Shinichi chuckled at the idea of having the device pointed _at_ him and clicking so fast the sounds merged into a single, solid beep.

She located the usual vein and inserted the needle, depressing the plunger to release the florbetaben. Shinichi watched the crook of his arm carefully, and Ai rolled her eyes. "You're not going to start glowing or some nonsense like that," she chided. "Now sit still for an hour to let it circulate before we begin the scans. Here's a laptop for you to read cases or browse the internet with." She handed him an older, heavy fifteen-inch laptop and wandered into one of the rooms to the side. Periodic beeping could be heard, as well as various frequencies of humming from whatever instrument was being warmed up. The professor swept in and out of the room, preparing it for his use as he typed emails and read case files from the TMPD's secured web user interface while sipping on cups of water.

After the hour was up, she had him change into a set of clean men's cotton sweats and guided him over to a giant machine that appeared similar in appearance to a standard MRI machine in its own enclosed room and had him sit on flatbed. "This is a positron emission tomography-magnetic resonance imaging scanner, or PET-MRI. The PET will scan for the florbetaben to create an image, while the MRI will scan using a generated magnetic field and pulses of radio wave energy to create an image. You don't have any metal implants or anything metal on you, do you?" When he answered negatively, she bade him lie down with his head closest to the circular portal. "This will take about two hours to do, since I want a full-brain scan. Try not to move too much while the machine is on and humming; the images will come out blurry otherwise. If you want, you can sleep during the procedure." She handed him a pair of foam ear plugs to dampen the volume of the humming that would commence once she began the procedure.

The next two hours passed with Shinichi dozing on the machine and Ai scrutinizing the top-to-bottom slices of deductive genius-brain images that slowly trickled onto her screen. What she found was worrying, though she needed to do some follow up work on his blood samples before she said anything more. And she had given Kaitou KID's suggestion some serious thought. Considering that he believed the apoptoxin was a possible cause of Shinichi's current mental deterioration, it was probably safe to assume that the phantom thief had given the inspector's plight some considerable contemplation. She was not sure exactly how far the magician's knowledge extended into medicine, but seeing as the gentleman thief made his own special mix of sleeping gas, he had to have a pretty decent grasp on biology, chemistry, biochemistry, and anatomy and physiology at a minimum. And creative genius that he was, it was possible that he might see another solution that she as a born and bred scientist would either outright dismiss or fail to see.

So now that she had decided to meet the thief in order see what could come out of a brainstorming session, how in god's name was she supposed to contact him? Then she realized, _If he's keeping tabs as closely as I think he is, he'll show up at my house soon enough._ Her eyes flicked to the observation window, where beyond Kudou Shinichi lay on the flatbed of the PET-MRI. _And I'll make sure that idiot on the machine is part of the conversation._

* * *

Author's Note: I am _terrible_ … I still can't believe I wrote this. Not quite sure where this one was going to take me when I began writing it. Apparently I like screwing over Shinichi as much as I do to Kaito. I'm on a medical kick, too. And holy _shit_ this was long! Coyoxauhqui, Mictlantecuhtli, Tlalocayotl, and Vitzlampaehecatl are Aztec deities. All medical-related stuffs were thoroughly researched (scientist, remember?)—it's amazing what you can find on the internet. I've decided to split it in two for more manageable reading. I hope you enjoyed it.

* * *

Completed: 20.07.2015


	2. II: Reincarnation

Detective Conan and Magic Kaito characters, settings, and ideas do not belong to me but to Aoyama Gōshō.

* * *

Guardian Angel

By Taliya

* * *

II: Reincarnation

* * *

"I'm back, Aoko!" called Kuroba Kaito as shut the front door behind him.

"Welcome home, Kaito!" Aoko's voice drifted towards him as he swapped his outdoor work shoes for house slippers in the genkan. He shuffled down the main hallway and into the kitchen-dining area of the Kuroba household, where Aoko was busy preparing dinner.

"Hey love," he murmured as he greeted her with a quick kiss to the cheek and washed his hands. His wife was in the process of making gyoza, her fingers nimbly sealing the edges of the dumpling wraps in neat, even folds. He eyed the two full trays she had already made. "You leave work early to make that many?" he asked as he poured a layer of sesame oil into a tall frying pan and set the heat on medium to warm up the pan.

Aoko sighed in affirmation. "Satou-keibu let me off the hook after a particularly bad case this afternoon." She shot her husband a wry grin. "I heard Otou-san explode this morning. That would not, by any chance, be your fault now, would it?"

Kuroba Aoko, formerly Nakamori Aoko, was Kaito's childhood sweetheart. When they were teens in high school, they had begun to become aware of each other in a way that was not strictly platonic. During Kaito's sixteenth year, he discovered that his father, Kuroba Touichi had not only masqueraded as the internationally wanted phantom thief Kaitou 1412, but that he had also been murdered because he had refused to seek out Pandora for them. In order to see his father's killers put behind bars, the young magician had taken up the iconic suit, cape, hat, and monocle in order to draw them out into the open.

Aoko had initially despised Kaitou KID for making a fool of her father during his thefts, and Kaito had been deathly afraid to tell her the truth. When they both went to college at Touto University, she had finally cornered him during the beginning their second year and forced him to confess after noticing how odd his behavior had become—not that anyone else would have known, but Aoko had known her friend since they were five, and she _knew_ something had been up. She had initially been appalled and furious beyond belief, but after she had had time—several months—to cool down and think it over, she understood that her best friend was, despite knowingly and willingly breaking the law, trying to fix a wrong that had gone uncorrected for far too long. And to that end, she had reluctantly offered to run interference for him, especially when people like Hakuba Saguru and a recently reemerged Kudou Shinichi, or even Hattori Heiji were around for a heist.

The pair had begun dating after Kaito's confession in spite of their conflicting class schedules and other… activities. Kaito had gone into medicine and Aoko into forensics. She now worked as an officer under Inspector Satou Miwako in Division One's Homicide Unit, and was therefore quite familiar with seeing Kudou Shinichi in police headquarters. Hakuba had joined the Division Two forces, working under her father Superintendent Nakamori Ginzo. The half-Japanese was an Inspector and the current head of the Kaitou KID Task Force.

The gentleman thief himself was a neurosurgeon, having taken his father's teachings to heart to save every life he could, and he specialized in neuro-oncology—brain tumors. Despite his ability to perform as a professional magician and the endorphin high he felt at the end of every show, nothing compared to the overwhelming relief and elation he experienced when he was able to tell his patient and the patient's loved ones that the cancer had gone into remission or was finally eliminated post-operation. Though to be fair, a successful KID heist came pretty damn close.

They lived in Kaito's home, next door to Aoko's house, so that the phantom thief could continue his search for the elusive Pandora. Kuroba Chikage had found herself a boyfriend during her travels around the world and currently lived with the accountant in Singapore. Kaito was expecting an announcement of marriage sometime in the coming months, and he could not be more pleased that his mother had once again found love.

Kaito laughed as he sat down at the dining table to fill the third tray of the pot stickers with his policewoman wife. "Maybe," he hedged with a cheeky grin on his lips, his fingers making quick work of wrapping the gyoza. "I hope this'll be the last one."

"You say that for every heist target," she rebutted affectionately. "Just don't give Otou-san a heart attack."

"You know I would never hurt anyone," he answered. His smile faded as a thought crossed his mind. "Aoko?" She hummed questioningly, her eyes on the half-made dumpling in her hands. "What do you think of Kudou Shinichi? Have you noticed anything different lately?"

She blinked and paused in her work, eyes swiveling upwards to stare quizzically at her husband. "Kudou-keibu?" she asked.

"Yup," Kaito said, his expression uncharacteristically serious.

"Hmm…" she mumbled as she collected her thoughts, considering his request carefully. "Kudou-keibu is in and out of the office like he usually is—much like I am too, so I don't see him all that much," she answered thoughtfully, gazing absently at the small ball of mixed pork and vegetables resting on the center of the dumpling wrap on her flour-dusted palm. "But whenever he and I are in the same vicinity, I have noticed—though not that often—that he sometimes spaces out for a while as if in a trance, and then wakes himself up. Other times he'll be doing something then seem to come to and not realize that he was doing whatever it was he was doing." She frowned. "It's really strange, now that I think about it." Aoko, after surviving college, had dropped her habit of referring to herself in the third person. She glanced at her best friend. "Is there something wrong with him?"

Kaito blew out a sigh. "I've noticed that too, during heists. His lapses are becoming more frequent and longer in duration, and it's worrying me." His eyes caught hers, and Aoko read the concern there. "I paid a visit last night to a close friend of his—Haibara Ai, a researcher in neurology and biochemistry, amongst other things—concerning his condition. Meitantei-san apparently hadn't told anyone, so it was news to her that his memory is failing. Both of us independently came to the conclusion that Kudou-san is suffering from the very beginning stages of early-onset Alzheimer's."

Aoko sucked in a sharp breath, eyes wide in shock. "You're serious?" she whispered.

The thief sighed again. "Unfortunately, yes. I'd suspected for a while, but wanted confirmation from someone else in the field," he murmured. "I then suggested that since it is an age-related disease, we might…" Kaito seemed to struggle with the words before he spit out, "… shrink him back."

The policewoman stuttered. "Sh-shrink him? Into Conan again?" Kaito had also explained the detective's brush with an organization of his own, and the effects of the experimental poison they had fed him from what he had gathered over the years as Kaitou KID. She had never let on to the detective she sometimes worked alongside that she knew of his past. "Will that halt his memory loss?"

"I don't know," Kaito sighed in frustration. "I honestly don't. For all Haibara-san and I hypothesized, he could be fully cured by shrinking, or maybe it'll set it back by a few years, giving us time to find a complete cure. Hell, it might even wipe his mind completely, since neither of us knows how additional poison will affect him. He still has both the drug and the antidote floating around in his blood, if I'm not off my mark."

Aoko finished wrapping the dumpling in her palm and placed it on the nearly full tray. Kaito set his down next to hers and peeled another wrapper from the stack. "So what are you going to do?" she asked quietly, watching her husband eye the amount of filling mixture and pinch a bit off with chopsticks.

He dabbed his finger in a small bowl of water and wetted the edge of the wrap before beginning to pleat one of the edges so that the dumpling would sit upright in the pan. He made five in quick succession, and Aoko marveled at how adept her husband's hands were, from all of his years of training as a magician. "If worst comes to worst and he loses his memory entirely, I'm considering who would be the best person to be his caretaker."

His wife frowned slight. "Shouldn't his parents suffice?"

Kaito snorted, though not unkindly. "Yuusaku-san and Yukiko-san left him alone when he turned fourteen, opting instead to fly around the world while avoiding Yuusaku-san's editors. Sounds a little negligent to me."

"And yet your mother did the same thing," Aoko quietly rebutted.

The phantom thief winced. "Well, she was actually tying up a few loose ends from her past life at the time," he said, and Aoko shook her head, wondering how she, a daughter from a long line of policemen, had ended up marrying into a family of phantom thieves. Even to herself, it sounded like some terrible fantasy drama. "His parents, on the other hand, travel around to escape their responsibilities for the most part."

Aoko regarded her childhood friend, who had grown from a scruffy, mischievous boy to the accomplished, handsome man she was proud to call her life partner. "So if worst comes to worst…?" she prodded.

Kaito took a deep breath. "I want to take care of him."

"Kaito…" Aoko breathed, speechless. "I—you realize what you are proposing is definitely _not_ a temporary solution? That—that you are asking someone to _live_ with us?"

"He doesn't have to live with us," the magician was quick to qualify. "But I just—" He sighed, struggling to explain his rationale. "He was the one who put Oyaji's killers in jail. Not me. I would have never been able to do something like that… not as Kaitou KID, and I… I _need_ to repay him somehow. I owe it to him." Kaito's eyes dropped to his lap for a moment before he lifted them to catch his wife's. "Even he doesn't remember, _I will_."

The policewoman had to look away from her husband. His eyes were so intensely sincere and so utterly grateful to the formerly shrunken detective. How could she refuse such a request? And considering Kuroba Touichi had been like a second father to her when she was young, she understood all too well where Kaito was coming from. She chuckled ruefully to herself, meeting Kaito's pleading and perplexed gaze. "Of course if it comes to that we'll take care of him." She gazed at her husband fondly. "I owe him too, you know."

Kaito finished filling out the tray, and the two of them carried the gyoza over to the stove where the frying pan was heated and ready. Kaito individually dropped the dumplings upright into the pan while Aoko arranged them as they sputtered and hissed. "So you know I'm going to make a visit with Haibara-san tonight to discuss Meitantei-san's condition again. Hopefully I won't be out for too long."

"He's important to you, whether he realizes it or not. To both of us," Aoko clarified. "Something like this… take as long as necessary." When the pot stickers were arranged neatly in concentric circles, Aoko added a centimeter's worth of water into the pan and covered it, washing her hands clean of flour and filling. Kaito, having already washed his hands, circled his arms around her waist and nuzzled and kissed her hair.

"Thank you," he whispered, and she leaned back into him with a content smile on her lips as her eyes fluttered shut, her now dried hands interlocking her fingers with his.

* * *

"Fancy meeting you here, Meitantei."

Shinichi started so badly he nearly flipped himself out of the armchair in Haibara's living room where he had been rereading _The Hound of the Baskervilles_. " _Shit,_ " the inspector swore fervently, his book having flown into some corner of the room as he gripped his chest with a hand. "Why can't you knock like a normal person?!" Shinichi wheezed.

The white-clad thief shrugged, examining the collar-style necklace featuring a massive fire opal. "That would defeat the purpose of being a phantom thief, don't you think, Meitantei? Pardon my intrusion," he announced belatedly as he flicked his wrist and disappeared the jewelry.

"Ah, konbanwa, KID-san," Ai greeted upon entering the room. "I figured you'd be back tonight."

Shinichi's eyes snapped to his friend. "You figured…" he parroted before cutting his gaze to the thief with a betrayed look. "That's right, you _told on me. To Haibara._ "

KID brushed imaginary lint off his ruffled shoulder clasps. "It's not like you would have sought help yourself, Meitantei. You're too stubborn."

"Like someone else I know," the detective muttered under his breath. Unfortunately for him, he was close enough to the scientist for her to hear him.

"Ara?" she cooed sarcastically, "And here I thought homicide detectives were the only ones who could out-stubborn headstrong phantom thieves."

"I'm hurt, ojou-san," KID said with an exaggerated pout. "To pick on poor defenseless me in such a manner!" The thief's gaze switched to the detective and his expression changed, going from playful to cautious in the span of a breath. "Meitantei…?" he queried softly, discretely checking the time on a pocket watch. The detective's eyes, normally bright with intelligence, had suddenly gone dull, as if the inner glow that spoke of a presence within had suddenly been snuffed out. There was also a slackness to his posture that was normally absent. Kudou swayed ever so slightly on his feet, his instinct and reflexes the only things keeping him upright.

Ai instantly caught the abrupt tension in the air, her eyes snapping to her friend's. "Kudou-kun?" she asked, stepping towards him but stopped at the abortive gesture from KID.

The thief was slowly easing his way closer, pausing at every step to repeat his question of, "Meitantei…?"

 _He's having a memory lapse right now,_ she realized with horror. _I understood in the abstract, but to actually_ see _it happening…_

By now KID had eased his way beside the incognizant inspector. "Meitantei…?" he murmured. "I'm going to lead you to that chair over there for you to sit down," he directed carefully, then proceeded to gently grasp Shinichi's hands and slowly walk him towards the chair he previously sat in. "That's it," KID coaxed, "now sit down." Gloved hands lightly pressed on the detective's shoulders, and the man sat mechanically in the chair, slumping slightly. KID kept his hands on Shinichi's shoulders to keep him upright, eyes intently watching the detective's for any sign of active awareness, and Ai was suddenly acutely aware of how much KID _cared_ for her friend.

It was… inspiring and humbling to see that her friend, her personal savior, held the loyalty of an internationally wanted criminal—the loyalty of Kaitou KID himself. Ai knew that the man behind KID's monocle was a certifiable genius—if a little (or okay, a lot) on the eccentric side. KID, had he felt so inclined, could have easily had the entire world at his mercy with the skills that he possessed. But the thief was a good person at heart, and years ago the gentleman thief had told Shinichi the reasons behind his thefts, who had then disclosed them to her. She wondered what kind of man KID was in his normal day to day life, if his flamboyant and cocky attitude was merely a part of the Kaitou KID costume and persona.

KID straightened after ensuring that the detective would not slump over in his seat before he turned his gaze upon her. "He's been out of it for ten minutes already," he informed her. "Do you have any results?" Though he had stepped away from the inspector, he remained in Shinichi's line of sight.

Ai nodded, crossing her arms across her chest. "PET scans showed higher than normal amounts of beta amyloid plaque in his brain, though the MRI did not show any unusual tissue growth or damage." The researcher eyed the magician speculatively. "Do you understand what I'm saying?"

The phantom thief nodded. "My specialty is in surgical neuro-oncology," he said simply, and Ai was stunned speechless.

KID _was a_ neurosurgeon _?!_ she thought dazedly.

"And what of his blood work?" he asked.

"I've managed to recreate the apoptoxin—it took me less time than I thought." In reality, because she had spent her entire life working on it, making the original after all the work on the antidote had been easy, though that was almost never the case. "I ran some tests, and he will de-age, as expected. I have no idea what it will do to his mental state, however."

"Fair enough," KID replied. He glanced at his pocket watch once more. "Fifteen minutes," he said softly, tucking the device away and shooting his rival a worried glance. "Do you think he'll take it?"

"I don't know," Ai replied, "since neither of us knows how his brain will react to the drug."

They had hit the eighteen-minute mark when Shinichi finally snapped to. The two doctors knew immediately when the detective jerked suddenly, his head bobbing unsteadily as he took in his surroundings. _Disorientation,_ Ai clinically catalogued in her mind, _temporary reduction in motor skills and delayed active recognition._

"Wha—?" Shinichi's gaze eventually focused on the figure in white. "Who're…?" he started before he asked uncertainly, "KID?"

"That's right, Meitantei," KID replied softly, sweeping towards the confused man. "Do you know where you are?"

"I…" He glanced around before he said, "Haibara's?"

"Yes, Kudou-kun," she answered, stepping into his line of sight and stopping by his side. Watching him come out of that episode had been one of the most painful things she had experienced—to see this intelligent man that had grown to be the brother she never had suddenly acting like a drowsy three year old tore at her heart. She kept a calm exterior though. There was no need to alarm him more.

Shinichi blinked. "I… had another episode, didn't I?" he asked resignedly as he came more fully back to himself.

KID nodded sorrowfully. "That's actually the reason why we're here," he said softly. He turned to Haibara, and she nodded resignedly, taking over the explanation.

"Kudou-kun," she said, and her heart clenched painfully. "We've—well, I've—diagnosed you with early-onset Alzheimer's." She swallowed thickly, hating herself for being the cause of Shinichi's expression crumpling into horror. "The scans and the blood work… They're indicative… Plus with the symptoms you've been exhibiting that were first recognized by KID—" She paused, breathing deeply to hold back the tears that demanded to make their presence known. " _I'm so sorry._ "

Shinichi sat in the chair, stunned, his jaw working soundlessly as he processed her analysis.

"While there are no proven cures now, Meitantei," KID picked up tentatively, "there is an option that might postpone any permanent damage to the brain." The detective's eyes latched onto KID's, silently pleading desperately for some miracle cure. "Trials have been able to reverse the effects of Alzheimer's in mice if the condition was caught in the earliest of stages. Unfortunately you are past that early detection stage. What we could do… is give you the apoptoxin to de-age you in the hopes that it will put the Alzheimer's in 'remission,' so to speak."

The inspector considered KID's offer carefully. After a long while of silence, he asked, "What are the risks?"

Again, KID and Ai traded unsure glances. "We don't know," Ai admitted. "We don't know if it would wipe away the plaque entirely, if it will simply go into remission, or if it'll even wipe your brain clean. We honestly have no idea."

"But as it stands I will assuredly lose my mind," Shinichi stated softly. "Is that correct?"

"Yes," the thief confirmed. "We cannot even give you percentages for chances of success."

Shinichi shakily exhaled. "Well that's it then, isn't it? I really don't have anything to lose by taking the poison."

"But you could lose your memory entirely!" Ai argued, fear adding a tremor to her voice as the first tears ran down her cheeks.

"Haibara," the detective said, gently grasping her hand. "If nothing else, then at least in this moment, I will have known that I did not idly sit by and passively accept my fate."

Ai laughed despite her tears. "That's just like you to say that, Kudou-kun," she said before nodding. "Alright. I'll go and get it." She disappeared into her laboratory, leaving the two males behind.

"Meitantei," KID murmured, and Shinichi turned his attention to the thief. "Kudou. Shinichi." KID paused, and Shinichi suddenly realized that the magician was nervous in the extreme.

"Yes, KID-san?" he asked, to verbally prod the suddenly tongue-tied smooth talker.

"I…" KID swallowed before trying again. "I… If, upon taking the apoptoxin you lose all of your memory… I would be— _gods_ this sounds terrible _any_ way I phrase this—it would be a privilege to be your caretaker."

Shinichi blinked, processing KID's offer. "Why?" he finally asked, honestly confused.

"Because I owe it to you," the thief said, "for putting Oyaji's killers in jail."

"Your father…?"

KID knelt before the detective and pulled off the top hat. "My father," he said as he took off the monocle, "and your godfather, Kuroba Touichi." And KID knelt barefaced before the surprised Shinichi. "My name's Kuroba Kaito. Pleased to meet you."

"Likewise," Shinichi replied mechanically, eyes drinking in KID's unadorned face.

A cough interrupted them, and KID—Kuroba—Kaito—replaced the hat and monocle in a flash. Ai ambled out of her lab, a slim, metal pillbox in one hand. Wordlessly, she presented the container to Shinichi, who opened it with equal parts dread, anxiety, and hope. The white and red capsule rested on a bed of foam, its shiny coating innocuously reflecting the lamplight. "It's your choice, Kudou-kun," Ai said thickly. "Neither of us is going to persuade you one way or the other." Shinichi's eyes drifted from the scientist's slightly red and blotchy face to the completely blank one of KID's.

"It's your decision," the thief confirmed.

Shinichi's gaze fell back to the small capsule, the one that had caused him more than several lifetimes' worth of trouble. "What of my assets and the like? I want my assets to go to whoever takes care of me in the event that I do lose my mind."

"That can be arranged," KID said, and Shinichi felt a little more of his anxiety lessen, knowing that the thief would help smooth things over in the aftermath if he was not there to do so himself.

"And my parents? Ran? Hattori?" he asked, suddenly reminded that if he did indeed lose his memory, he would not know them.

"We can postpone this so that you have time to think it over and talk to them," Haibara said neutrally.

The detective closed his eyes. "I would like that, now that my panic is over for the moment." He opened his eyes to gaze gratefully at the two standing before him. "I'll let you know when I'm ready."

* * *

Over the next two weeks, Shinichi discussed his condition and his future plans with his parents, Haibara, the Hondous, the Hattoris, and the Kurobas.

His parents had offered to settle in the Kudou home to take care of him if things went south, but Shinichi gently but firmly rebuffed their offer. His parents, despite being in their late fifties, were too flighty to remain in one place for too long, and by the inspector's reckoning, stability of any kind—location included—would be key. Ran and Eisuke had also offered their home to him, but with a baby due in seven months, Ran would be too busy with an infant to care for a deteriorating invalid. The same excuse went for Heiji and Kazuha, who was six months along.

The Kurobas, however, were not so easily dissuaded. Shinichi had argued for placing himself in a care facility with nurses to help him so that he would not be a burden. Kaito and Aoko were having none of it. Kaito had finally won the argument by saying, "Kudou-san, normally I steal jewels, but I'm pretty sure I could pull off a heist where a person was the target if I wanted to." And having had chased Kaitou KID for almost two decades, Shinichi had little doubt Kaito could pull it off, and so he grudgingly acceded to their request. The next week after was spent getting his documents in order.

The four couples gathered at Haibara's home for moral support, each of them praying to every deity they could think of for a good outcome. Shinichi and Ai had locked themselves in the third bedroom attached to her laboratory while the eight guests loitered nervously in the living room.

A piercing shriek split the air, and they hugged each other with gritted teeth as Shinichi's cries of pain grew louder. The screaming continued for several minutes, the detective's voice finally softening into piteous, broken moans. By this point Yukiko was buried in Yuusaku's chest sobbing, with Ran, Kazuha, and Aoko in similar positions. The husbands had their arms curled tightly around their wives, though they too shuddered as tears crept down their faces.

At length the scientist opened the door to her lab and the eight people practically lunged at her, stopping short of colliding with her once they beheld the bundle in her arms. "It seems there was an unexpected side effect," she murmured tiredly. In her arms was a five-year-old boy, whom she had swathed in blankets. The child was asleep, with residual beads of sweat dotting his brow and traces of tears flowing from his closed eyes.

"Shin-chan," Yukiko murmured in astonishment.

"Do you think…?" Kaito began, his question trailing away uncertainly.

Ai caught his eye. "Somehow I think the addition of apoptoxin overwhelmed the antidote, though I don't understand how or why. The amounts were equal, so I'm not sure what went wrong…"

"Does he remember anything?" asked Ran apprehensively.

The researcher shook her head. "We'll know once he wakes up," she said and carried him over to the couch to settle him. The adults hovered about the room, too nervous to sit still for more than a few minutes. Kaito and Ai quietly discussed theories with each other in a corner, while Aoko conversed with the Hattoris and the Hondous chatted with the Kudous.

A small moan instantly silenced the entire room, and all eyes turn to the small boy in their midst, who was beginning to wake up. They all flocked to ring the couch, desperate to see if Kudou Shinichi's memory remained. The child opened his eyes then shrunk back upon seeing so many faces staring intently at him. He pulled the blankets up to his nose, shielding his face while keeping his eyes on his spectators.

"Shin-chan?" Yukiko whispered hopefully with tear-blurred vision. "Do you know who I am?"

The boy's eyes—bright, intelligent eyes—roved from face to face, but there was no spark of recognition. There was a collective instantaneous realization among the group that stunned them more thoroughly than the detonation of a nuclear warhead.

Kudou Shinichi, Edogawa Conan, Kudou-kun, Shin-chan, Tantei-kun, Meitantei—whatever name he had once responded to—the person who had responded to those varied names—that person was gone.

Yukiko released a wail of despair and was quickly engulfed in Yuusaku's embrace. Ran had stood, shell-shocked and insensate, and Eisuke had made his excuses and guided his unresponsive wife out to door to take her home with the Hattoris in tow, as they were staying with the Hondous for their visit to Tokyo. Heiji had stared numbly at the small child in disbelief, only able to mutter a repeated, mournful, "Kudou…" He too had to be led out by his wife.

Ai had crumpled to the ground, her expression the epitome of devastation. " _What have I done?_ " she whispered, anguish and self-repugnance lacing her voice. Kaito had scooped her off the ground soon after and deposited her in the armchair, an arm around Aoko's quivering shoulders and a hand resting bracingly on one of Ai's. Aoko had retrieved the frightened youth, propping him on a hip and murmuring soothing words in his ear.

"You couldn't have known," the thief murmured, rubbing Aoko's arm soothingly as she pressed against him, still holding the twice-shrunken Shinichi. "Just like I—" his voice broke, "—couldn't have either. We can't blame ourselves for not anticipating this outcome."

"But I should have known better!" the scientist snapped. "I'd worked on this for _years_! I should have known _all_ the possible side effects of the apoptoxin!"

"But Kuroba-san's right, Haibara-san," Yuusaku said, inserting himself into the doctors' stilted conversation. "You informed Shinichi that there were many unknowns, and he accepted the risk." Ai bowed her head, recognizing the truth of the mystery writer's words.

The remaining five adults watched the boy settle sleepily in Aoko's arms. "I suppose," Kaito said, "Aoko and I are his guardians now, unless you would like to take him," he said to the Kudous.

Yukiko shook her head even as she reached out to smooth Shinichi's ever-present cowlick. "Much as I would love to, I don't think I'd be able to look at him and not burst out crying," the retired actress admitted wearily. She glanced at her husband, and he squeezed her once around the shoulder. "Plus, we're getting on in age. I don't think we'd be able to keep up with a five year old constantly. Shin-chan trusted you enough to sign over his assets, and I trust his judgment."

Yuusaku nodded in agreement. "We'll help you financially in any way. All you have to do is ask, since you are taking care of our boy. You're more than welcome to live in our house since we'll be traveling, but we'll stop by often to see him." The Kudous left soon after, promising to open a joint checking account with the Kurobas for any of Shinichi's expenditures and to mail the couple a set of house keys for the Kudou home.

Aoko sat down on the couch, still cuddling the child. "He's so small," she said softly as Kaito settled next to her. Ai watched the trio from her spot in the armchair.

"Haibara-san," Kaito began, "Would you mind being his godmother?"

Ai felt her throat close up. "I—I couldn't possibly—" she stuttered, choking, "—not after what I've done to him—!"

"We can think of no one better," Aoko said warmly. "Yes, you made mistakes, but you would move mountains to help him."

The researcher ducked her head as she fought to control her tears. With a breathless mix of a sob and a laugh, Ai breathed, "I would be honored!"

The Kurobas beamed at her, their sincerity and gratitude overwhelming. The trio basked in their newfound bond of kinship, reveling in the warmth of their solidarity at protecting the little boy who slept peacefully amongst them.

"Are we changing his name?" Aoko asked quietly, so as not to disturb her newly adopted son.

"He keeps his first name," Kaito said decisively, softly carding his fingers through Shinichi's hair. "Though I guess it'd be better if we change his last name to Kuroba," he added reluctantly. He had no desire to completely sever the boy from his true past.

"Kuroba Shinichi," Ai murmured, eyes watching the thirty-five-turned-five-year-old boy who had helped her take down an entire criminal syndicate. "Edogawa Conan."

Kaito grinned sadly. "Tantei-kun," he said fondly as he gently stroked the boy's cheek. He lifted his eyes to meet his wife's. "We'll need to buy an entire collection of Sherlock Holmes for him to read."

Ai watched the newly created family unit and could not help but think of that one night, when KID had first appeared in her home with concerns regarding Kudou Shinichi's health solely on his mind. That Kuroba Kaito was Kaitou KID made sense to the scientist. She curled into the armchair and watch the three of them, Kaito in particular, and could not help but think, _Guardian angel indeed._

* * *

Author's Note: So… yeah. I should also add in that I don't know exactly what people do when they have a mental lapse and sort of made that up, as I couldn't find any sort of data about it on the internet. And apparently I was spot on the money: uncontrolled apoptosis can cause neurodegenerative diseases, one of which is Alzheimer's. I hope you enjoyed it.

* * *

Completed: 20.07.2015


End file.
